Navistar/International Cummins ISB 6.7L DEF Head Unit
NAVISTAR/INTERNATIONAL CUMMINS ISB 6.7L DEF HEAD UNIT
ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY
WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 2321-11-2 ( OEM Part Number 4353000C92 ). This part is primarily made for a Cummins ISB 6.7L, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here
Additional Notes: QLS DEF Header, 297mm
OEM NUMBERS
| Primary OEM | 4353000C92 |
| Additional OEM | 2515990C1, 2515990C3, 4087159C91, 4097721C91, 4163689C91, 4254212C91, 4353000C92 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490541030 |
| WEIGHT | 8.00 LBS |
SHIPPING OPTIONS
Ship Weight : 8.00 LBS
UPS Ground, 2nd Day Air, Next Day Air
SHIPPING POLICY
Tamerx Diesel Products ships via UPS Ground. Next day air shipping can be arranged for a reasonable price of anywhere from $50.00 - $100.00 depending on the weight of the product and your location. We will do everything we can to make sure that you get the service you need. We understand how important it is to receive your order as quickly as possible.
In most cases Tamerx Diesel Products only needs one address, as long as your product is shipping to the same location as your billing information. In order to eliminate credit card fraud, your billing information must match the credit card you provide.
The terms, conditions, and details of our warranty vary from product to product. Specific warranty details can be found below.
Tamerx Diesel Products provides a replacement warranty on all of our parts. The duration and mileage limitations of the warranty vary by product and are specified on the product's detail page/item listing.
Please note that the warranty covers replacement of the part and the cost of shipping the replacement part to you only. It does not cover any shop, labor, towing, or any similar or related costs. This is not a "money back guarantee".
If you experience a problem with your part or it is not functioning properly, the correct warranty procedure is to call us at (510) 257-1777 (8:00 AM - 5:00 PM ET Monday through Friday). Be sure to have your order number and/or other relevant order information ready so we can easily locate your order and resolve your issue as quickly as possible. From that point, we will review with you any troubleshooting steps that may need to be taken and other areas or systems that can be checked to rule out external problems contributing to your part's issue. If a replacement is determined to be necessary, we will then arrange for your replacement part to ship out ASAP and issue any necessary return shipping labels and/or documents.
As is the case for the majority of the diesel products sold on Tamerx Diesel Products, your part's warranty is active as soon as you install it. In some other cases, warranty activation is contingent upon you sending us your core (i.e., your old part). Tamerx Diesel Products will provide you a return shipping label for parts that have a warranty with a core return condition. When we have received your core return, the part's warranty coverage begins. We reserve the right to void the product warranty if your core is not received within the allotted time, or if it isn't received at all. If the warranty for the diesel part you are purchasing has a core return requirement, it will be clearly noted on the product detail page/item listing.
What is a Core Charge?
A core charge (also called "core deposit") is similar to the deposit you might pay for a can or bottle of soda and is a standard requirement in the auto parts industry. For example, in many states, to promote recycling, you pay a deposit when you purchase a can of soda and receive your deposit back when you return the empty can. Many automotive parts have a core charge, or core price, that works in essentially the same way as a soda can deposit.
30 Day Core Charge Hold
You authorize Tamerx Diesel Products, to hold your credit card for the specified core charge amount and that you agree to return your core with 30 days of receiving the purchased part. When we have received your core return, the hold is released and the core charge payment is canceled.
The customer, or parts buyer, is responsible for any shipping costs associated with core returns unless otherwise specified in the product listing/detail page. Tamerx Diesel Products offers prepaid UPS shipping labels (SKU numbers UPS-CR1 and UPS-CR2) for use in returning your core that are available for purchase on our website during your shopping/order process.
The shipping label you will need to use for the core return is dependent upon what part you are purchasing. UPS-CR1 is good for cores weighing up to 20 pounds. UPS-CR2 is appropriate for shipping cores weighing 21 pounds or more. You must include enough information with the core return that clearly identifies it as a.) a Core Return, and b.) contains enough information we can use to clearly associate the core return with your order. Including a copy of the invoice or packing slip that came with the original shipment, clearly marked "Core Return", is ideal. Alternately, you can include a note marked as "Core Return" that includes your order number, full name and address, and phone number or other contact information. Failure to include this information with your returned core will most likely delay any due core credit being issued and/or delay any applicable warranty activation. Core returns need to be for the exact part purchased and cannot be damaged. Substituting another part in place of the part you have purchased is not acceptable.
All fluids must be drained.
If you have purchased a set or a parts package, you will need to return cores for all components of the set. For example, if you have purchaed a high pressure oil pump with an IPR valve, you will need to return both HPOP and IPR valve cores to receive proper credit. If you have purchased an EGR cooler/EGR valve package, your core return must consist of an EGR cooler core and an EGR valve core, or core credit will not be given.
Core Charges are often mandated by state legislature, and, as such, the actual core charge and taxes on the charge may vary depending on the state in which you buy your part. The Tamerx Diesel Products core charge presented to you online today with your item is representative of the most common core charge.
The Navistar/International Cummins ISB 6.7L DEF Head Unit: OEM 4353000C92 provides precise monitoring and dependable function for the diesel exhaust fluid system in compatible Navistar equipment. Manufactured to OEM specifications, this unit measures DEF level, temperature, and quality to help maintain emissions compliance and consistent aftertreatment performance. Its rugged design ensures durability in demanding operating conditions, protecting both the exhaust system and overall engine efficiency. Choosing an OEM DEF head unit minimizes compatibility issues and supports long-term reliability. This component is a trusted solution for keeping Navistar Cummins-powered machinery running smoothly and without interruption.
PEOPLE ALSO ASKS | BLOG(S)
The DEF Head Unit is a module mounted on the Diesel Exhaust Fluid (DEF) tank in Navistar / International vehicles with Cummins ISB 6.7L engines. It combines several sensors, fluid routing, and monitoring functions into one assembly. Its job is to make sure the DEF system works properly, helping your truck stay emissions compliant and run smoothly.
What It Actually Does
- Monitors DEF Level
- It senses how much DEF fluid is in the tank, sending this info to the engine control system so you’re alerted before the level gets critically low.
- Measures Fluid Temperature
- DEF can freeze or lose effectiveness when too cold. The head unit keeps track of fluid temperature so the system can compensate or warn if it’s outside the safe range.
- Checks Fluid Condition / Quality
- Some versions include sensors that detect contamination or improper DEF quality. This helps prevent damage to downstream components and ensures dosing is accurate.
- Filters Particulates
- The unit includes internal filtration (a screen or mesh) to remove debris or particles from the fluid before it enters more sensitive parts of the emissions system.
- Routes Fluid (Suction & Return)
- It includes plumbing or ports that pull DEF out of the tank (suction), send it toward the dosing system, and allow unused fluid to return to the tank, keeping fluid flow stable and preventing air pockets.
- Communicates with the Engine Control Module (ECM)
- All the sensors feed data back to the ECM. If something is out of spec — like fluid too low, too cold, or quality bad — the ECM can alert the driver, reduce power, or trigger maintenance codes.
If the DEF Head Unit works as intended, it helps ensure your SCR emissions system reduces NOₓ properly, avoids warnings and derates, and protects downstream parts (injectors, catalysts, etc.). If it fails, you may see:
- Warning lights
- Power reduction or engine derate
- Possible damage to DEF injectors or the SCR catalyst
- Potential non‑compliance with emissions regulations
Keeping this unit in good working order is key to reliability, avoiding costly repairs, and staying compliant with emissions laws.
The DEF (Diesel Exhaust Fluid) head unit is a vital part of your diesel vehicle’s emissions system. It monitors DEF level, temperature, and quality—allowing the system to function properly and stay compliant with environmental regulations. But like any sensor-driven component, it has a finite service life.
Average Lifespan of a DEF Head Unit
A typical DEF head unit can last anywhere from 100,000 to 150,000 miles, or approximately 5 to 7 years under normal conditions. However, this lifespan can vary based on how the vehicle is used and maintained.
Factors That Affect Longevity
Several conditions may shorten or extend the life of your DEF head unit:
- DEF fluid quality
- Contaminated or expired fluid can damage internal sensors
- Temperature extremes
- Prolonged exposure to freezing or high heat affects performance
- Crystallization
- Dried DEF buildup can clog sensors and ports
- Wiring condition
- Corrosion or moisture in connectors may interfere with signal accuracy
- Maintenance habits
- Regular checks and clean DEF usage help prevent early failure
With proper care and attention, a DEF head unit can last for many years. Watch for early warning signs to avoid unexpected derates or system faults.
It should be inspected during routine maintenance or when DEF-related fault codes appear.
Yes, it may cause failed inspections and regulatory penalties.
An inaccurate “empty tank” reading even when the DEF tank is full.
Yes, a new OEM unit restores proper DEF monitoring and SCR operation.
Cummins DEF Head Units
